When a semiconductor chip is mounted on a supporting member, silver paste is conventionally used, for the most part, as the die bonding material to bond the semiconductor chip with the supporting member. However, as semiconductor chips become smaller with higher performance and the supporting members used also become smaller and more miniaturized, methods that employ silver pastes are presenting problems including paste bleed-out and wire bonding troubles due to sloping of the semiconductor chip. In recent years, therefore, adhesive films (adhesive films for semiconductors) have come to be used in place of silver pastes.
Systems used to obtain semiconductor devices using adhesive films include short bar attachment systems and wafer back-side attachment systems.
In a short bar attachment system, short bars are cut out by cutting or punching from a reel-shaped adhesive film and the short bars of the adhesive film are bonded to a supporting member. Individuated semiconductor chips are joined to the supporting member by a separate dicing step, via the adhesive film bonded to the supporting member. A semiconductor device is then obtained, if necessary by a wire bond step, sealing step, or the like. In short bar attachment systems, however, a special assembly apparatus is necessary to cut out the adhesive film into short bars and bond them to the supporting member, and therefore production cost has been higher than methods using silver paste.
In a wafer back-side attachment system, first an adhesive film and dicing tape are attached in that order to the back side of a semiconductor wafer. The semiconductor wafer is diced for partitioning into a plurality of semiconductor chips, and the adhesive film is cut for each semiconductor chip. Next, the semiconductor chips are picked up together with the adhesive films laminated on their back sides, and the semiconductor chips are bonded to supporting members through the adhesive films. A semiconductor device is then obtained by further steps such as heating, curing and wire bonding. A wafer back-side attachment system does not require an assembly apparatus for individuation of the adhesive film, and a conventional assembly apparatus used for silver paste may be used either in its original form or with part of the apparatus modified by addition of a heating plate or the like. Among methods that employ adhesive films, therefore, this method has been of interest with the aim of helping to limit production cost.
Methods proposed for dicing semiconductor wafers, on the other hand, include stealth dicing, in which a semiconductor wafer is irradiated with laser light to selectively create reformed sections inside the semiconductor wafer, and the semiconductor wafer is cut along the reformed sections (Patent documents 1 and 2). In this method, dicing tape is stretched to apply stress to the semiconductor wafer, and the semiconductor wafer is partitioned into multiple semiconductor chips along the reformed sections.    [Patent document 1] Japanese Unexamined Patent Publication No. 2002-192370    [Patent document 2] Japanese Unexamined Patent Publication No. 2003-338467